KR20070036409A - Liquid crystal display and driving method thereof - Google Patents

Abstract

The present invention relates to a liquid crystal display and a driving method thereof capable of reducing power consumption. A liquid crystal panel having a liquid crystal cell formed at each intersection of a horizontal gate line and a data line in a vertical direction, a gate driver for applying a gate signal to the gate line, and a polarity inverted for at least three liquid crystal cell units in a vertical direction The present invention provides a liquid crystal display including a data driver for applying a data signal whose polarity is inverted for each liquid crystal cell unit adjacent to each other in a horizontal direction, and a driving method thereof. As such, the polarization pattern of the data signal may be inverted in units of at least three liquid crystal cells to adjust the swing width of the data signal, thereby reducing power consumption of the liquid crystal display.

Liquid crystal display, liquid crystal panel, data signal, timing controller, polarity

Description

Liquid crystal display device and method for driving thereof

1 is a view schematically showing a conventional liquid crystal display device.

2A and 2B are diagrams for explaining a method of driving a liquid crystal panel of a single dot inversion method.

3 is a schematic view of a liquid crystal display device according to the present invention;

4A and 4B illustrate an embodiment for driving a liquid crystal panel.

5A and 5B are views for explaining another embodiment for driving a liquid crystal panel.

6 is a view for explaining another embodiment for driving a liquid crystal panel of the present invention.

<Explanation of symbols for the main parts of the drawings>

2, 100: liquid crystal panel 6, 200: gate driver

4, 300: data driver 10, 600: timing controller

400: gamma power supply unit 500: power supply unit

The present invention relates to a liquid crystal display device and a driving method thereof, and more particularly, to a liquid crystal display device and a driving method thereof capable of reducing power consumption.

The liquid crystal display displays an image by adjusting light transmittance of liquid crystal cells according to a video signal. The liquid crystal display device is implemented in an active matrix type in which switching elements are formed in each cell, and is applied to display devices such as computer monitors, office equipment, and cellular phones. As a switching element used in an active matrix liquid crystal display device, a thin film transistor (hereinafter, referred to as TFT) is mainly used.

1 is a view schematically showing a conventional liquid crystal display device.

Referring to FIG. 1, in the conventional liquid crystal display, m × n liquid crystal cells Clc are arranged in a matrix type, and m data lines D1 to Dm and n gate lines G0 to Gn are arranged. A liquid crystal panel 2 that crosses and a TFT is formed at an intersection thereof, a data driver 4 for supplying a data signal to the data lines D1 to Dm of the liquid crystal panel 2, and gate lines G0 to A gate driver 6 for supplying a scan signal to Gn and a timing controller 10 for controlling the data driver 4 and the gate driver 6 by using a synchronization signal supplied from the system.

As the driving method of the liquid crystal display, inversion driving methods such as a frame inversion system, a line column inversion system, and a dot inversion system are used.

The frame inversion type liquid crystal panel driving method inverts the polarity of the pixel data signal supplied to the liquid crystal cells on the liquid crystal panel every time the frame is changed. In the liquid crystal panel driving method of the line inversion method, polarities of pixel data signals supplied to liquid crystal cells are inverted according to a line (column) on the liquid crystal panel. The dot inversion scheme allows each of the liquid crystal cells on the liquid crystal panel to be supplied with pixel data signals having a polarity opposite to that of the pixel data signals supplied to adjacent liquid crystal cells in the vertical and horizontal directions. The polarities of the pixel data signals supplied to the liquid crystal cells are reversed. Of these inversion driving methods, the dot inversion method provides an image having excellent image quality compared to the frame and line inversion methods.

Accordingly, the dot inversion method is mainly used in recent years. The dot inversion method is divided into a 1 dot inversion method and a 2 dot inversion method.

2A and 2B illustrate polarities of pixel data signals supplied to liquid crystal cells of a liquid crystal panel by using a one dot inversion liquid crystal panel, divided into odd frames and even frames.

In the odd frame and even frame shown in FIGS. 2A and 2B, it can be seen that in the one-dot inversion scheme, the polarity of the pixel data signal is driven so that the polarity of the pixel data signal is changed in units of one dot. This one-dot inversion method provides the best picture quality among the inversion methods because the polarity of the data signal is changed in units of one dot. However, the one-dot inversion method consumes a lot of power because the period of the pixel data signal, which is the output of the data driver, changes with the change of one gate line.

Accordingly, the present invention has been made to solve the above problems, and the liquid crystal display device and the driving method thereof which can reduce the power consumption of the liquid crystal display device by inverting the polar pattern of the data signal in units of at least three liquid crystal cells. Its purpose is to provide.

A liquid crystal panel in which a liquid crystal cell is formed at each intersection of a horizontal gate line and a data line in a vertical direction, a gate driver for applying a gate signal to the gate line, and at least three liquid crystal cell units in a vertical direction The present invention provides a liquid crystal display including a data driver for applying a data signal whose polarity is inverted for each other and whose polarity is inverted for each liquid crystal cell unit adjacent to each other in the horizontal direction.

The timing controller may further include a timing controller configured to control the data driver and the gate driver by using a synchronization signal and to generate a polarity control signal for inverting the polarity of the data signal.

The data signal has an amplitude of at least three times or more the amplitude of the gate signal, and it is effective to have a positive polarity and a negative polarity.

Of course, the data driver may include a first data driver connected to an odd data line and a second data driver connected to an even data line. In this case, it is effective to include a first data signal applied by the first data driver and a second data signal applied by the second data driver, and the first and second data signals have an inverted polarity.

The R, G, and B signals may be applied to the above three liquid crystal cells in the vertical direction to form one pixel, and the polarity of the adjacent pixels may be inverted.

Further, a liquid crystal panel in which a liquid crystal cell is formed at each intersection of a horizontal gate line and a vertical data line according to the present invention, a gate driver for applying a gate signal to the gate line, and a data signal applied to the data line A method of driving a liquid crystal display device comprising a data driver, the method comprising: inverting polarity of at least three liquid crystal cell units in the vertical direction and inverting polarity of one liquid crystal cell unit adjacent in the horizontal direction. It provides a driving method.

The method may include sequentially applying a gate signal to the gate line to turn on a plurality of liquid crystal cells connected to one gate line, and performing odd-numbered data on a first data signal whose polarity is inverted after at least three gate line turns on. And applying a second data signal having a polarity inverted with the first data signal to an even data line.

In this case, the first and second data signals may be applied by a single data driver or by different data drivers.

Preferably, the gate driver and the data driver are controlled by a timing controller and the data signal is changed according to a polarity control signal of the timing controller having an amplitude of at least three times or more than the gate signal.

The R, G, and B signals may be applied to the above-mentioned three liquid crystal cells in the vertical direction to form one pixel, and the polarity of the adjacent pixels may be inverted.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention in more detail. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various forms, and only the embodiments are intended to complete the disclosure of the present invention, and to those skilled in the art to fully understand the scope of the invention. It is provided to inform you.

3 is a schematic view of a liquid crystal display according to the present invention.

Referring to FIG. 3, in the driving apparatus of the liquid crystal display according to an exemplary embodiment of the present invention, m × n liquid crystal cells Cp are arranged in a matrix type, and m data lines D1 to Dm and n gates are provided. The liquid crystal panel 100 in which lines G0 to Gn intersect and a TFT is formed at an intersection thereof, and a gate driver 200 for supplying scan signals to gate lines G0 to Gn of the liquid crystal panel 100. A data driver 300a or 300b for supplying a data signal to the data lines D1 to Dm, a gamma voltage supply unit 400 for supplying a gamma voltage to the data driver 300, and the driver. The data driver 300 and the gate driver 200 by using the power supply unit 500 for supplying power to the fields 200 and 300 and the gamma power supply unit 400, and a synchronization signal supplied from the system 700. At least three pixel cells And a timing controller 600 for supplying the polarity control signal for inverting the property to the data driver. In addition, the present embodiment includes a DC / DC converter for generating a voltage for supplying the liquid crystal panel by boosting or reducing the voltage input from the power supply unit 500. In this case, the DC / DC converter generates a gamma reference voltage VDD, a gate high voltage VGH, a gate low voltage VGL, a common voltage Vcom, and the like.

Here, the system 700 supplies the vertical / horizontal synchronization signals Vsync and Hsync, the clock signal DCLK, the data enable signal DE, and the data R, G, and B to the timing controller 600. .

The liquid crystal panel 100 includes a plurality of liquid crystal cells Cp formed in a matrix at the intersections of the data lines D1 to Dm and the gate lines G0 to Gn. Each TFT formed in the liquid crystal cell Cp supplies a data signal supplied from the data lines D1 to Dm to the liquid crystal cell Cp in response to a scan signal supplied from the gate line G. In addition, a storage capacitor Cst is formed in each of the liquid crystal cells Cp. The storage capacitor Cst is formed between the pixel electrode of the liquid crystal cell Clc and the front gate line, or is formed between the pixel electrode of the liquid crystal cell Clc and the common electrode line to maintain a constant voltage of the liquid crystal cell Clc. Let's do it. The common voltage Vcom is supplied from the DC / DC converter to the common electrode, which is one electrode of the liquid crystal cell Clc.

In the present embodiment, the data driver 300 includes a first data driver 300a for applying a pixel data signal to an odd data line and a second data driver 300b for applying a pixel data signal to an even data line.

The first and second data drivers 300a and 300b supply pixel signals of at least three or more lines to odd and even lines, respectively, in response to data control signals from the timing controller 600. In particular, the data driver 300 converts the digital pixel data R, G, and B from the timing controller 600 into an analog pixel signal using a gamma voltage from a gamma voltage generator (not shown). .

In detail, the data driver 300 shifts the source start pulse SSP according to the source shift clock SSC to generate a sampling signal. Subsequently, the data driver 300 sequentially receives and latches the video data signals R, G, and B in predetermined units in response to the sampling signal. In addition, the first and second data drivers 300a and 300b convert the latched pixel data R, G, and B for at least three lines into analog pixel signals and supply them to the data lines DL1 through DLm. The odd and even lines are supplied separately. In this case, the first and second data drivers 300a and 300b convert the polarity of the positive and negative pixel data signals to at least 3 dots inversion or more according to the polarity control signal supplied from the timing controller 600. do.

The gamma voltage supply unit 400 supplies a plurality of gamma voltages to the data driver 300.

The gate driver 200 sequentially supplies the gate high voltage VGH to the gate lines G0 to Gn in response to the gate control signals GSP, GSC, and GOE from the timing controller 600. Accordingly, the gate driver 200 causes the thin film transistor TFT connected to the gate lines G0 to Gn to be driven in units of gate lines. Specifically, the gate driver 200 shifts the gate start pulse GSP according to the gate shift pulse GSC to generate a shift pulse. The gate driver 200 supplies the gate high voltage VGH to the corresponding gate line GL for each horizontal period H1, H2,... In response to the shift pulse. In this case, the gate driver 200 supplies the gate high voltage VGH only during the enable period in response to the gate output enable signal GOE. The gate driver 200 supplies the gate low voltage VGL to the gate lines GL1 through GLn in the remaining periods in which the gate high voltage VGH is not supplied. In addition, the gate driver 200 supplies the gate low voltage VGL to the gate line G0 formed at the uppermost side for the storage capacitor Cst of the first scan line.

In addition, the timing controller 600 controls to control the gate driver 200 and the data driver 300 by using the vertical / horizontal synchronization signals Vsync and Hsync and the clock signal DCLK input from the system 700. Generate signals. In the present exemplary embodiment, the timing controller 300 generates a polarity control signal for inverting the data polarity pattern of the pixel data signals in units of at least three liquid crystal cells and supplies the same to the data driver 300. At this time, since the data driver 300 is separated into the first and second data drivers 300a and 300b by odd and even lines, the polarity control signal is also separated into the first and second polarity control signals. In addition, it is preferable that the polarities of the first and second polarity control signals are applied in reverse. That is, it is preferable to use the first polarity control signal inverted to the second polarity control signal.

Hereinafter, the driving method of the liquid crystal display device according to the embodiment of the present invention having the above-described configuration will be described.

4A and 4B are diagrams for describing an exemplary embodiment for driving a liquid crystal panel.

4A and 4B, in this embodiment, the polarity control signal of the timing controller 600 reverses each other in the positive polarity (+) and the negative polarity (−) for each of the three liquid crystal cells in the vertical direction. In the horizontal direction, one adjacent liquid crystal cell is inverted to have a positive polarity (+) and a negative polarity (−).

In other words, when the liquid crystal cells are arranged in an 8x8 matrix as shown in FIG. Is applied, and negative polarity (-) is applied to (1,4) to (1,6). Positive (+) is applied to (2,1) to (2,3), (2,7) and (2,8), and negative (-) is applied to (2,4) to (2,6). ) Is applied. In this way, the positive (+) and the negative (-) are inverted alternately in the row direction, and the positive (+) and the negative (-) are reversed three times in the column direction.

In the present embodiment, the timing controller 600 applies the same polarity to three liquid crystal cells connected to one data line, and then generates the inverted polarity control signal.

As a result, when three liquid crystal cells connected to one data line have a positive polarity, three liquid crystal cells have a negative polarity, and the three liquid crystal cells then again have a positive polarity. Will have

At this time, the first polarity control signal and the inverted second polarity control signal are generated to apply the first polarity control signal to the first data driver 300a and the second polarity control signal to the second data driver 300b. Is authorized. Through this, the first polarity control signal applied to the first data driver 300a is applied to the odd-numbered data line connected to the first data driver 300a and the second polarity applied to the second data driver 300b. The control signal is applied to the even-numbered data line connected to the second data driver 300b. Thus, if three liquid crystal cells connected to the first data line have a positive polarity, the three liquid crystal cells connected to the second data line adjacent to the first data line have the opposite negative polarity. .

In more detail, first, when a logic high gate signal is sequentially applied to the first to third gate lines, the liquid crystal cells connected to the first to third gate lines are sequentially turned on. At this time, a positive data signal is applied to the three liquid crystal cells connected to the odd data lines connected to the first data driver 300a, and the even number connected to the second data driver 300b is applied. The data signal of the negative (-) state is applied to three liquid crystal cells connected to the data line of. Subsequently, when a logic high gate signal is sequentially applied to the fourth to sixth gate lines, the liquid crystal cells connected to the fourth to sixth gate lines are sequentially turned on. At this time, a negative data signal is applied to the three liquid crystal cells connected to the odd data lines connected to the first data driver 300a, and the even number connected to the second data driver 300b is applied. Data signals of a positive polarity state are applied to the three liquid crystal cells connected to the data lines of.

This inverts the data signal by inverting the state of the polarity control signal of the timing controller 600 whenever the three gate signals change, and inverts the odd and even data lines through different data drivers 300 to different polarities. The 3-dot inversion scheme is implemented by applying the polarity control signal to the data line.

When the above driving method is implemented, power consumption of the liquid crystal display device can be reduced. That is, when the conventional liquid crystal display consumes about 70mW of power, it consumes about 20mW in the gate driver, about 40mw in the data driver, and about 10mW in the logic circuit. However, when the 3 dot inversion method according to the present embodiment is used, the power consumption of the data driver is reduced by about 50% or more, so that the drive can be performed within 20 mW.

The present invention is not limited to the above description, and the polarity inversion scheme according to three or more liquid crystal cells can be used by controlling the polarity inversion period of the polarity control signal. That is, a method such as a 4-dot inversion method or a 5-dot inversion method may be implemented.

5A and 5B are diagrams for describing another exemplary embodiment for driving a liquid crystal panel.

Referring to FIGS. 5A and 5B, the widths of the data signals applied by the first and second data drivers 300a and 300b are adjusted so that the positive and negative polarities of the four liquid crystal cells in the vertical direction are adjusted. Are inverted from each other, and one liquid crystal cell adjacent in the horizontal direction is inverted to be positive (+) and negative (-).

That is, in the liquid crystal cells connected to the odd-numbered data line receiving the data signal from the first data driver 300a, the value of the data signal is inverted every fourth period, and the data signal is received from the second data driver 300b. In the liquid crystal cells connected to the even-numbered data line, the value of the data signal is inverted every fourth period. The data signals output from the first and second data drivers 300a and 300b are inverted from each other.

In this case, the first and second data drivers 300a and 300b apply the data signal to the data line according to the polarity control signal of the timing controller 600. Therefore, the period of the liquid crystal cell whose polarity is inverted may be adjusted by adjusting the amplitude of the polarity control signal of the timing controller 600.

In more detail, the driving described above is first applied to the first to fourth gate lines, and when the gate signals of logic high are sequentially applied, the liquid crystal cells connected to the first to fourth gate lines are sequentially turned on. At this time, the positive polarity (+) signal is applied to the four liquid crystal cells connected to the odd data lines connected to the first data driver 300a, and the even number connected to the second data driver 300b is applied. The signals of the negative (-) state are applied to the four liquid crystal cells connected to the data lines. Thereafter, when a logic high gate signal is sequentially applied to the fifth to eighth gate lines, the liquid crystal cells connected to the fifth to eighth gate lines are sequentially turned on. At this time, a negative signal is applied to the four liquid crystal cells connected to the odd-numbered data lines connected to the first data driver 300a, and the even-numbered signals connected to the second data driver 300b are applied. The signals of the positive (+) state are applied to the four liquid crystal cells connected to the data lines.

As described above, whenever the four gate signals change, the state of the polarity control signal of the timing controller 600 is also inverted, and thus the polarity of the data signal applied to the data line is also inverted. In addition, the odd- and even-numbered data lines are applied to the data lines by applying polarity control signals having different polarities through different data drivers to implement the 4-dot inversion scheme.

Of course, the present invention is not limited thereto, and the dot inversion scheme of the three-dot inversion scheme and the four-dot inversion scheme may be used by adjusting the amplitude of the polarity control signal of the timing controller.

6 is a view for explaining another embodiment of driving the liquid crystal panel of the present invention.

In the present invention, the data driver 300 is divided into two data drivers 300a and 300b and applied to the upper and lower portions of the liquid crystal panel, respectively. As shown in FIG. The data driver 300 may apply data signals to a plurality of data lines according to the polarity control signal of the timing controller 600. In addition, as shown in FIG. 6, R, G, and B signals may be applied to three liquid crystal cells in the vertical direction, respectively, and defined as one pixel, and a driving method of inverting the polarity of adjacent pixels may be used. .

As described above, the present invention can reduce the total number of swings of the data lines applied through the data driver, thereby reducing the power consumption of the entire device. That is, as shown in FIG. 2A, when the polarity of the unit liquid crystal cell changes, the swing of the data signal changed through the data driver must be performed eight times in total. However, as shown in FIG. 5A, when the polarity is changed per four liquid crystal cells, the swing of the data signal changed through the data driver is reduced twice in total. Accordingly, when the polarities of the n liquid crystal cells are changed, a swing width of 1 / n times may be reduced, thereby reducing power consumption.

As described above, the present invention can reduce the power consumption of the liquid crystal display by reversing the polar pattern of the data signal in units of at least three liquid crystal cells.

Although the invention has been described with reference to the accompanying drawings and the preferred embodiments described above, the invention is not limited thereto, but is defined by the claims that follow. Accordingly, one of ordinary skill in the art may variously modify and modify the present invention without departing from the spirit of the following claims.

Claims (11)

A liquid crystal panel in which liquid crystal cells are formed at intersections of the gate lines in the horizontal direction and the data lines in the vertical direction; A gate driver applying a gate signal to the gate line; And a data driver configured to apply a data signal to the data line, wherein the polarity is inverted for at least three liquid crystal cell units in a vertical direction and the polarity is inverted for each liquid crystal cell unit adjacent in a horizontal direction. The method according to claim 1, And a timing controller for controlling the data driver and the gate driver by using a synchronization signal and generating a polarity control signal for inverting the polarity of the data signal. The method according to claim 1, And the data signal has an amplitude of at least three times or more the amplitude of the gate signal, and has positive and negative polarities. The method according to claim 1, And the data driver comprises a first data driver connected to an odd data line and a second data driver connected to an even data line. The method according to claim 4, And a first data signal applied by the first data driver and a second data signal applied by the second data driver, wherein the first and second data signals have polarities inverted from each other. The method according to claim 1, And R, G, and B signals applied to the three liquid crystal cells in the vertical direction to form one pixel, and inverting the polarity of the adjacent pixels. A liquid crystal panel having a liquid crystal cell formed at each intersection of a horizontal gate line and a data line in a vertical direction, a gate driver applying a gate signal to the gate line, and a data driver applying a data signal to the data line In the driving method of the liquid crystal display device, And inverting polarity of at least three liquid crystal cell units in the vertical direction and inverting polarity of one liquid crystal cell unit adjacent to each other in the horizontal direction. The method according to claim 7, Sequentially turning on a plurality of liquid crystal cells connected to one gate line by sequentially applying a gate signal to the gate line; Applying a first data signal whose polarity is inverted to the odd-numbered data line after at least three gate line turns on, and applying a second data signal having the polarity inverted from the first data signal to the even-numbered data line; Method of driving a liquid crystal display comprising a. The method according to claim 8, And the first and second data signals are applied from a single data driver or from different data drivers. The method according to claim 7, And the gate driver and the data driver are controlled by a timing controller and the data signal is changed according to a polarity control signal of the timing controller having an amplitude of at least three times or more of the gate signal. The method according to claim 7, And applying R, G, and B signals to the three liquid crystal cells in the vertical direction to form one pixel, and inverting the polarity of adjacent pixels.

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